Anti-surge coil spring assembly



Oct. 4, 1966 E. L. LAST ETAL ANTI-SURGE COIL SPRING ASSEMBLY Filed March2, 1964 INVENTORS EVERTON L. LAST BY CONRADA TE/CHERT United StatesPatent 3,276,760 ANTI-SURGE COIL SPRING ASSEMBLY Ever-ton L. Last andConrad A. Teichert, both of Grand Rapids, Mich., assignors to GeneralMotors Corporatlon, Detroit, Mich., a corporation of Delaware Filed Mar.2, 1964, Ser. No. 348,329

3 Claims. (Cl. 267-1) This invention rel-ates generally to fuelinjection apparatus for internal combustion engines, and particularly tothe fuel injector plunger return spring assembly.

In fuel injection units it is a common practice to use a coil spring toreturn the fuel metering plunger to a retracted position after theplunger has been actuated and fuel injected into the combustion chamberof an engine. It will be appreciated that when an impulse is imparted tosuch a coil spring as the plunger is retracted, the impulse travels thelength of the spring and is reflected back. If the natural frequency ofthe spring is low, one such impulse will not be materially dampenedbefore one or more succeeding impulses are imparted to the spring withthe result that the spring is caused to surge. Such surging material-1yeffects the position of fuel metering grooves in the plunger assemblywith a resultant decrease in eificiency of the unit.

It is the primary purpose of this invention to overcome such heretoforeencountered difficulties by providing a spring damping means whichdampens or attenuates spring vibrations that may develop duringoperation of a spring assembly.

It is a more specific object of this invention to provide a dampingmeans which is disposed between two coil springs and provides africtional damping force therebetween.

It is a further object of this invention to provide a spring dampingmeans employing a sliding friction member which may be adjusted to varythe darn-ping rate without requiring additional machining of any of theparts comprising the damping assembly.

Other objects and advantages of the present invention will be moreclearly understood from the following description having reference tothe drawing wherein:

FIGURE 1 is a sectional view of a portion of a 'housing member of aninternal combustion engine and its fuel injection apparatus showing thecomponents of the subject invention in an assembled relationship.

FIGURE 2 is a perspective view of the spring separating ring shown inFIGURE 1 illustrating one embodiment of the present invention.

FIGURE 3 is a perspective view of a further embodiment of the separatingring of FIGURE 2.

FIGURE 4 is a perspective view illustrating another embodiment of theseparating ring of FIGURE 3.

Referring now in detail to the drawing, and first to FIGURE 1, a fuelinjection device embodying the subject invention incorporates a housingmember 1 to which is secured fuel supply connections 2 and 3 in theconventional manner. The housing member 1 includes a chamber 4 whichreceives a reciprocating plunger designated generally as 5.

A slide piece 9 forms the upper port-ion of the reciprocating plungerand transmits its motion to an injector member 10. The lower end of theinjector member 10 slid-ably reciprocates in a pump cylinder 11 which isrigidly secured in the housing member 1 by a nut \12 threaded to thehousing as at 13. The structure and operation of the lower pumpingcylinder -11 to effect discharge of fuel from a spray tip 14 is similarto that shown in Patent No. 2,997,994 to RF. 'Fa-lberg and forms no partof this invention.

The upper end of the slide piece 9 has an outer end surface 15 formedthereon. A shoulder 16 is formed on the underside of the upper end ofslide piece to seat a coil spring as hereinafter described.

A guide means 17, integral with the housing 1, has a slot \18 thereinwhich receives the end 19 of a'guide pin 20. The guide pin is slidablypositioned in a chamber 21 of the slide piece 9 and is biased against aretaining ring 22 by a spring 23 disposed between the end surface 24 ofthe guide pin and a retaining ring 25 secured to the slide piece.

A shoulder or spring seat 26 is provided on the housing member 1adjacent the guide means 17 to receive a coil spring as hereinafterdescribed. The outer surface 27 of the guide means is adapted to receivea separating ring, designated generally by the numeral 28, in slidingrelation.

The separating ring, as illustrated more clearly in FIG- URE 2, has anaxially extending sleeve 29. A radially extending flange 32 formedintegral 'with the axially extending sleeve 29, is disposed intermediatethe ends of the axially extending sleeve and divides it into two endportions 30 and 31. Surfaces 33 and 34, shown in FIG- URE 1, of theradially extending flange 32 act as spring seats for the coil springs 35and 36, respectively, when the separating ring is in its assembledposition. The inner surface 37 of the axially extending sleeve 29 isformed to a dimension which provides a sliding frictional contact withthe outer surface 27 of the guide means 17.

The coil spring 35 in interposed between the shoulder 16 of the slidepiece 9 and the separating ring 28, with one end of the spring abuttingthe shoulder 16 and the other end abutting the surface 33 of theradially extending flange 32. The coil spring 36 is interposed betweenthe shoulder 26 on the housing member 1 and the separating ring 28 withone end of the spring abutting the shoulder 26, and the other endseating against the surface 34 of the radial flange 32. The end portions30 and 31 of the axially extending sleeve 29 are received within theinner diameters of the coil springs 35 and 36, respectively. The springs35 and 36 may have either equal or different spring rates.

FIGURES 3 and 4 illustrate [further embodiments of the separating ring.FIGURE 3 shows the separating ring 28 having a radial slot 38 throughboth the radially extending flange '32 and the axially extending sleeve29 to form a discontinuous ring. FIGURE 4 illustrates a radiallyextending flange 32 having a plurality of slots 39 therein with one ofthe slots 38 passing through both the radial flange and the axialsleeve.

Referring again to FIGURE 1, a contact wheel 40, rotatably mounted on alever 41, contacts the outer surface 15 of the slide piece 9 and impartsaxial motion to the plunger member 5 from an external source in theconventional manner.

In operation, axial motion is imparted to the plunger member 5 throughthe contact wheel 40 and the lever 41. Downward mot-ion of the slidepiece 9 causes the coil springs 35 and 36 to be compressed, resistingdownward movement of the plunger member. The separating ring 28, beinginterposed between the ends of the springs 35 and 36 will also be moveddownwardly as the springs are compressed. The inner surface 37 of theseparating ring 28 illustrated in FIGURE 2, having been formed toprovide a sliding friction fit when in engagement with the outer surface27 of the guide means 17, will create a friction force tending to opposemovement of the separating ring.

When the plunger member has reached its predetermined maximum downwardposition, upward movement of the lever 41 will allow the springs 35 and36 to return the plunger member 5 to its outermost position, maintainingthe outer surface 15 of the slide piece 9 in contact with the wheel 40.Expansion of the springs 35 and 36 during retraction of the plungermember causes the separating ring 28 to return to its original positionwith the frictional force created bysliding contact of the surface 37 onthe guide member 17 tending to oppose such movement.

It can be readily understood that as the plunger member reciprocates ata high rate and the springs 35 and 36 are compressed and relaxed, theseparating ring 28 will undergo reciprocating motion on the guide means17. The ifrictiona l force created between the inner face 37 of theseparating ring and the outer surface 27 of the guide means will alwaysbe in a direction tending to oppose movement of the separating ring,thus acting to dampen axial vibrations induced in the coil springs andprevent surging of the plunger member.

Using a separating ring as shown in FIGURE 3, which constitutes oneembodiment of the present invention, the 1 frictional force between theinner riding surface 37 of the axially extending sleeve 29 and the outersurface 27 of the guide means 17 may be controlled through radialadjustment of the separating ring, such adjustment being readilyallowable by provision of the slot 38. An increase in friction forcewould be desirable when the injection apparatus is to be operated at ahigh frequency where the danger of the springs surging would beincreased.

In the event that the injection apparatus is to he operated underconditions where adjustment of the separating ring to vary theaforementioned friction force is desirable, the slots 39 provided in theradially extending flange 32, as shown in FIGURE 4, will allow radialadjustment of the separating ring without distortion of the radiallyextending flange. Such distort-ion is undesirable in that it wouldaffect the seating of the coil springs 35 and 36 on the surfaces 33 and34, respectively, of the radially extending flange with a resultantcocking or tilting of the separating ring, thereby reducing the ringsef- 'fectiveness in damping vibration.

It is appreciated that various minor changes in the construction andarrangement of the .parts may be made without departing from the spiritand scope of the invention as hereinafter defined. I

What is claimed is:

1. In a fuel injection device including a housing memher having achamber therein receiving a reciprocating plunger, a guide meansintegral with said housing member,

said plunger being disposed within said guide means, a

separating ring slidably disposed about said guide means, saidseparating ring including an axially extending sleeve and a radiallyextending flange intermediate the ends of said axially extending sleeveand integral therewith, a (first coil spring interposed between theouter end of said plunger and said radial flange, and a second coilspring interposed between said housing member and said radial flange,said separating ring frictionally engaging said. guide means toattenuate vibration of said springs.

2. In a fuel injection device including a housing member having achamber therein receiving a reciprocating plunger, a guide meansintegral with said housing member, said plunger being disposed withinsaid guide means, a separating ring slida-bly disposed about said guidemeans, said separating ring including an axially extending sleeve and aradially extending flange intermediate the ends of said axiallyextending sleeve and integral therewith, a first coil spring interposedbetween the outer end of said plunger and said radial flange, and asecond coil spring interposed between said housing member and saidradial flange, said separating ring frictionally engaging said guidemeans and having a slot therethrough to form a discontinuous ring whichmay be radially adjusted to vary the frictional force between said ringand said guide means to change the dampening eflect of said separatingring.

3. A device as described in claim 2 wherein said radially extendingflange has a plurality of slots therein to allow radial adjustment ofsaid separating fling without distortion of said radially extendingflange.

References Cited by the Examiner UNITED STATES PATENTS ARTHUR L. LAPOINT, Primary Examiner.

W. B. WILBUR, R. M. WOHIJFARTI'I,

Assistant Examiners.

1. IN A FUEL INJECTION DEVICE INCLUDING A HOUSING MEMBER HAVING ACHAMBER THEREIN RECEIVING A RECIPROCATING PLUNGER, A GUIDE MEANSINTEGRAL WITH SAID HOUSING MEMBER, SAID PLUNGER BEING DISPOSED WITHINSAID GUIDE MEANS, A SEPARATING RING SLIDABLY DISPOSED ABOUT SAID GUIDEMEANS, SAID SEPARATING RING INCLUDING AN AXIALLY EXTENDING SLEEVE AND ARADIALLY EXTENDING FLANGE INTERMEDIATE THE ENDS OF SAID AXIALLYEXTENDING SLEEVE AND INTEGRAL THEREWITH, A FIRST COIL SPRING INTERPOSEDBETWEEN THE OUTER END OF SAID PLUNGER AND SAID RADIAL FLANGE, AND ASECOND COIL SPRING INTERPOSED BETWEEN SAID HOUSING MEMBER AND SAIDRADIAL FLANGE, SAID SEPATATING RING FRICTIONALLY ENGAGING SAID GUIDEMEANS TO ATTENUATE VIBRATION OF SAID SPRINGS.